The present invention relates to a preliminary stage of a container processing machine, particularly of a bottle filling machine, and especially on a bottle filling machine that has one or more processing stations. Provided are a container inlet for containers that are to be processed, a container outlet for processed containers, and transport elements for effecting the flow of containers between the inlet and outlet, with at least one of the transport elements comprising a transport star, which rotates about a vertical shaft, and a restraining element. The transport star has a peripheral surface that concentrically encircles the axis of rotation of the latter and that is provided with a plurality of uniformly spaced recesses that are radially open in the direction of said peripheral surface and serve to transport the containers along a circular path from an inlet of the transport star to an outlet thereof. The restraining element is disposed to the side of the circular transport path opposite the peripheral surface of the transport star.
It is known, in general, to provide container processing machines, such as filling machines, closure machines, and labelling machines, with a so-called preliminary stage, i.e. a machine region that is provided with transport elements, via which the bottles or containers that are to be handled or processed are fed to the processing station of the machine, which processing station is provided with the processing elements, or via which, after the processing, the bottles are removed from the station and are withdrawn from the machine. Thus, the preliminary stage forms the actual container inlet and container outlet of the overall machine, which comprises the preliminary stage and processing station, with at least two transport elements being provided at the preliminary stage for the flow of containers. One of these transport elements feeds to the processing station of the machine those bottles that at the inlet side are supplied at a prescribed distance and distribution via a conveyor belt and inlet screw mechanism. Another of the transport elements withdraws the processed containers out of the processing station and hence out of the machine. Especially with container or bottle filling machines that have a number of processing stations, such as a filling station and a closure station, it is customary to also associate with the preliminary stage the closure station for filled containers or bottles. The preliminary stage is then provided with at least three transport elements, and in particular again one transport element for supplying the containers that are to be filled to the container or bottle filling station, another transport element in the form of a transfer element for withdrawing the filled containers or bottles from the filling station and transferring them to the closure station, as well as a further transport element for withdrawing the closed containers or bottles from the closure station and for passing them on, for example to a subsequent conveyor belt that withdraws the containers or bottles.
In order to deliver the containers at the required spacing or distribution, and in order to assure a frictionless receiving and transfer of the containers, each of the aforementioned transport elements is embodied as a transport star, the periphery of each of which is provided with a plurality of recesses (pockets) that are open toward the periphery, are distributed at the same angular spacing, and serve to receive containers. Each of the containers received by the recesses of the transport stars is moved by the latter along a partial circular conveying path. In order to retain or restrain the containers in the recesses of the transport stars, a restraining element is furthermore provided along the partially circular conveying stretch of each star. This restraining element encircles the partially circular conveying stretch of the pertaining transport star between the inlet and the outlet of that star. In this connection, the inlet of the transport star marks the beginning of the partially circular conveying stretch, and the outlet of the transport star marks the end of such conveying stretch. With the heretofore known preliminary stages, these restraining elements are externally disposed guide regions or guide curves, each of which forms a fixed guide surface for the containers and encircles the partially circular conveying stretch of the pertaining transport star. In order to assure that the containers are reliably retained in the recesses of the conveying stars, the distance between the guide surface and the axis of rotation of the respective transport star must be adapted to the diameter of the containers that are disposed in an upright manner in the recesses of the transport stars.
Since, for example in beverage-processing plants, containers or bottles of various sizes or diameters must often be processed with the container canning machines that are present there, it is necessary with the heretofore known preliminary stages, prior to changing from one container or bottle size to another container size or type, to adjust the guide regions or guide curves to the new container size, or to exchange the existing guide regions for new regions that are adapted to the new container size. This requires extensive and time-consuming changeovers. A further drawback of the heretofore known preliminary stages is that as a result of the sliding guidance of the containers along the guide surfaces of the guide areas, and on the sliding surfaces on which the bottoms of the containers slide, it is not possible to have a vibration-free transport of the containers, nor a transport of the containers without a certain inherent movement, such as a rotational movement about the vertical axis of the container. The latter is a drawback especially in the region of those transport stars (transfer stars) that serve as transfer elements, because a nonvibration-free transport of those containers that are filled and are being transferred with these transport stars from the filling station to the closure station can lead to a loss of the contents from the containers, for example if the latter foam over. Since furthermore with the heretofore known preliminary stages the containers are held in the recesses of the transport stars with "play", a relatively high noise level also results during transport of the containers with the transport stars.
In order to achieve a certain amount of simplification of the changeover of preliminary stages for various container sizes, it was proposed in German Offenlegungsschrift 34 32 590 Sindermann et al dated Mar. 13, 1986, to use different guide regions for different container sizes, with common centering devices being provided in the preliminary stage to hold these guide regions, and with the latter being centrally arrested via rapid tensioning mechanisms that are operated electrically, hydraulically, mechanically, etc. However, despite a relatively expensive and complicated construction, it is not possible with these heretofore known preliminary stages to eliminate the need for changeover when processing different sizes of containers.
It is an object of the present invention to improve a preliminary stage of the aforementioned general type in such a way that it is possible to process containers of various sizes or diameters without the need to undertake changeover measures with regard to the guide regions, and that in addition the containers can be held in a play-free manner in at least that transport star that serves as a transport element.